The invention relates to a transmission shift lever assembly which has a lever which can be moved in longitudinal and transverse directions.
It is well known to provide an agricultural tractor with a manually operable transmission shift lever. Such a lever cooperates with transmission elements to transmit information corresponding to the movement of the lever to a vehicle gearbox or to a gearbox control. Such a shift lever can be used to select differing gear ratios or groups of the vehicle gearbox. The shift lever can also be used to engage neutral positions or a park position.
Shift levers can be pivoted in two directions about two perpendicular axis along a shift path established by a shift gate. The shift gate may have a double xe2x80x9cHxe2x80x9d shape, which has a central neutral channel and two or three transverse channels. By moving the shift lever in an end region of one of the transverse channels, a gear ratio or a group of the gearbox can be selected and engaged. With such shift levers, the lever must be tilted during shifting.
DE-A-199 22 010 shows a sliding block which is fastened to a shift lever which interacts with quadrants of two transmission elements. By pivoting the shift lever in the longitudinal direction the sliding block can be moved from one quadrant to another quadrant, in order to select one of the quadrants. By pivoting the shift lever in the transverse direction the sliding block acts upon the selected quadrant and shifts the associated transmission element that is connected to the vehicle gearbox, whereby a gear ratio or a group of the vehicle gearbox is engaged.
It would be desirable to have a shift lever which is ergonomically designed and which has a compact configuration.
An object of the present invention is to provide a shift lever which is ergonomically designed and which has a compact configuration.
This and other objects are achieved by the present invention wherein a manually operated shift lever or selector lever is movable in a longitudinal direction and a transverse direction to select and engage differing gear ratios and/or gearbox groups and to select a park position. Transmitting levers transmit signals to a vehicle gearbox corresponding to the movement of the lever. The shift lever is coupled to a retainer or a bridge, and a pair of arms form four bar linkage which connects the retainer with a pair of plates.
A pair of rods interconnect and extend between the plates The shift lever is pivotally coupled to the rods by pairs of arms which form four-bar linkages. By varying the spacing between the ends of the arms, the pivot center or virtual pivot axis of rotation of the shift lever can be positioned near to or far from the shift lever in either direction, from minus infinity to plus infinity. If the arms are equally long and parallel to each other, then the pivot center will be located at infinity.
The virtual pivot axis of the shift lever can be positioned so that the shift lever moves with little or no tilting. Despite a relatively short lever length and relatively small longitudinal movement of the shift lever, comparatively large actuating movements are possible. Therefore, the shift lever assembly can be relatively small and compact and with improved ergonomics. The compact configuration and the reduced lateral movement of the shift lever permits a favorable positioning on a vehicle platform. The lever movements are short and uncomfortable tilting of the hand during shifting is avoided.
Preferably, one end of each arm is pivotally coupled to the retainer so that each arm is pivotal in a longitudinal direction with respect to the retainer. Preferably, the other end of each arm is pivotally coupled to one of the rods so that each arm is pivotal in a longitudinal direction with respect to rods and with respect to the housing. All these pivot axes are therefore parallel to each other.
Preferably, the shift lever is fixed to a central region of a bridge-shaped retainer, and a pair of arms are coupled to each side of the retainer. The resulting assembly has substantially symmetrical configuration and has an optimum force distribution, so that assembly can be relatively small and compact. A thrust piece is fastened on each side of the retainer. The thrust pieces interact with contact pieces of transmitting levers which are arranged between the thrust pieces.
Several transmitting levers are pivoted about a pivot pin which interconnects the housing members, each of which can transmit a corresponding signal to another device, such as the vehicle gearbox. Each of the transmitting levers has a contact piece which have contact surfaces thereon. A thrust piece is carried on by shift lever or by the retainer. By moving the shift lever in the longitudinal direction the thrust piece is brought into a position next to and opposite a contact surface of a selected transmitting lever. When the shift lever is moved in the transverse direction, the thrust piece engages contact surface and pivots the selected transmitting lever out of its neutral position, for example, into a gear ratio position.
Preferably, a plurality of transmitting levers are arranged between the two housing plates. For compactness, the transmitting levers are pivoted on a central longitudinal pivot pin which interconnects the housing plates. Each contact piece has two contact surfaces located opposite each other, each of which interacts with an associated thrust piece.
Preferably, the transmitting levers are provided with legs which can be connected with linkages which can be coupled to a vehicle gearbox. For example, shifting control cables can be hooked into openings in the legs. Also, sensors or switches may be arranged near to the legs, for transmitting shift signals to a gearbox control. Electrical switches could be integrated into the spacing elements
Spacing elements are positioned between each adjacent pairs of transmitting levers. The spacing elements do not pivot with the transmitting levers, but are fixed to the housing members.